Content Playback Program, Content Playback Method, and Content Playback System

ABSTRACT

It is an object of the present invention to play back other content on any timing without being restricted to the embedded timing of watermark data embedded in the content even when the progress time of the content fluctuates. The content playback program in the present invention causes a computer to realize: a first table for associating and storing a synchronization point ID embedded as watermark data with a scheduled timing for the synchronization point based on a synchronization reference timing for the main content; a second table for storing a scheduled start timing for first sub-content based on the synchronization reference timing; a detection function for detecting the synchronization point ID embedded as watermark data from second sub-content played back based on the progress of the main content; an acquisition function for acquiring the scheduled timing for the synchronization point based on the detected synchronization point ID and the first table, and acquiring the difference between the scheduled timing of the acquired synchronization point and the detection timing for the synchronization point ID based on the synchronization reference timing; a determination function for determining a start timing for the first sub-content based on the acquired difference and the second table; and a control function for controlling playback of the first sub-content based on the determined start timing for the first sub-content.

TECHNICAL FIELD

The present invention relates to a content playback program, contentplayback method, and content playback system.

BACKGROUND ART

Many services have arisen in recent years that comprehensively produceevents by allowing various types of content, such as video and music, tobe played back on a plurality of devices. In these services, theprogress of each type of content has to be synchronized between thedevices. In the synchronization process, for example, the playbacktiming for sub-content is set beforehand in certain devices in order toalign various types of sub-content with content such as the mainperformance (the “main content”) and each of the items of sub-content isplayed back at the set timing.

However, in live performances where actors and singers appear on stage,the progress time of the live performance may fluctuate with eachperformance. As a result, it is difficult to preset the playback timingfor sub-content such as background music (BGM) to align with maincontent that is a live performance.

A method has been proposed in Patent Document 1 to address this problemfor main content such as video accompanied by audio and sub-content suchas second screen information on the video (subtitles, etc.) in which thesecond screen information is outputted to a mobile device based on theprogress of the video.

In this disclosed method, electronic watermarking technology is used toembed identification information for second screen informationassociated with each scene in the video as watermark data in the audiofor the video, which is outputted along with the audio for the video. Inthe mobile device, data for second screen information is associated andstored with this identification information so that, when audio for thevideo is inputted to the mobile device, the watermark data can bedetected and the second screen information synchronized with the videoscene can be outputted. Here, “watermark technology” refers to anytechnology used to embed specific information as watermark data in soundfor video or music content.

This method can be used to embed watermark data in sub-content such asbackground music sent along with a live performance such as actors orsingers performing on stage even though the progress time for liveperformances fluctuates so that separate sub-content such as secondscreen information is outputted based on the progress of the maincontent.

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: JP 2015-61112 A

SUMMARY OF THE INVENTION Problem Solved by the Invention

However, the method disclosed in Patent Document 1 associates watermarkdata embedded in each video scene with identification information forsecond screen information based on a 1:1 correspondence. As a result,second screen information can only be outputted for each video scenebased on the timing of the embedded watermark data. This creates aproblem in which second screen information such as subtitles cannot beoutputted on the timing in the beginning, middle and end of each videoscene which is unrelated to the timing of the embedded watermark data.

Therefore, it is an object of the present invention to provide a contentplayback program, content playback method, and content playback systemfor playing back other content on any timing without being restricted tothe embedded timing of watermark data embedded in the content even whenthe progress time of the content fluctuates.

Means of Solving the Problem

One aspect of the present invention is a content playback programcausing a computer to realize: a first table for associating and storinga synchronization point ID embedded as watermark data with a scheduledtiming for the synchronization point based on a synchronizationreference timing for the main content; a second table for storing ascheduled start timing for first sub-content based on thesynchronization reference timing; a detection function for detecting thesynchronization point ID embedded as watermark data from secondsub-content played back based on the progress of the main content; anacquisition function for acquiring the scheduled timing for thesynchronization point based on the detected synchronization point ID andthe first table, and acquiring the difference between the scheduledtiming of the acquired synchronization point and the detection timingfor the synchronization point ID based on the synchronization referencetiming; a determination function for determining a start timing for thefirst sub-content based on the acquired difference and the second table;and a control function for controlling playback of the first sub-contentbased on the determined start timing for the first sub-content.

Another aspect of the present invention is a content playback methodcomprising the steps of: associating and storing a synchronization pointID embedded as watermark data with a scheduled timing for thesynchronization point based on a synchronization reference timing forthe main content in a first table; storing a scheduled start timing forfirst sub-content based on the synchronization reference timing in asecond table; detecting the synchronization point ID embedded aswatermark data from second sub-content played back based on the progressof the main content; acquiring the scheduled timing for thesynchronization point based on the detected synchronization point ID andthe first table, and acquiring the difference between the scheduledtiming of the acquired synchronization point and the detection timingfor the synchronization point ID based on the synchronization referencetiming; determining a start timing for the first sub-content based onthe acquired difference and the second table; and controlling playbackof the first sub-content based on the determined start timing for thefirst sub-content.

Another aspect of the present invention is a content playback systemhaving a user terminal and an operator terminal, wherein the userterminal comprises a first table for associating and storing asynchronization point ID embedded as watermark data with a scheduledtiming for the synchronization point based on a synchronizationreference timing for the main content, a second table for storing ascheduled start timing for first sub-content based on thesynchronization reference timing, a detecting unit for detecting thesynchronization point ID embedded as watermark data from secondsub-content played back based on the progress of the main content, anacquiring unit for acquiring the scheduled timing for thesynchronization point based on the detected synchronization point ID andthe first table, and acquiring the difference between the scheduledtiming of the acquired synchronization point and the detection timingfor the synchronization point ID based on the synchronization referencetiming, a determination unit for determining a start timing for thefirst sub-content based on the acquired difference and the second table,and a control unit for controlling playback of the first sub-contentbased on the determined start timing for the first sub-content; and theoperator terminal comprises an input unit for receiving input related tothe playback of the second sub-content from an operator, and a controlunit for controlling playback of the second sub-content based on thecontent of the received input.

In the present invention, a “unit” may refer to either a physical meansor a function of a unit realized by software. Also, the function of asingle “unit” or device may be realized by two or more physical means ordevices, and the functions of two or more “units” or devices may berealized by a single physical means or device.

Effect of the Invention

The present invention is able to provide a content playback program,content playback method, and content playback system for playing backother content on any timing without being restricted to the embeddedtiming of watermark data embedded in the content even when the progresstime of the content fluctuates.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing the configuration of the content playbacksystem in an embodiment of the present invention.

FIG. 2 is a diagram showing an example of the hardware configuration ofthe user terminal 200 and the operator terminal 100.

FIG. 3 is a diagram showing an example of the function configuration forthe operator terminal 100.

FIG. 4 is a diagram showing an example of the function configuration forthe user terminal 200.

FIG. 5 is a diagram showing an overview of the content playback processin the content playback system.

FIG. 6 is a diagram showing an overview of the content playback processin the content playback system.

FIG. 7 is a diagram showing an example of the table configuration in thecontent playback system.

FIG. 8 is a flowchart showing an example of the content playbackprocessing in the user terminal 200.

FIG. 9 is a diagram showing an overview of an example of a contentplayback event.

FIG. 10 is a diagram showing an overview of the content playbackcontrols in the content playback system for the event in FIG. 9.

FIG. 11 is a flowchart showing an example of the content playbackcontrol processing in the user terminal 200.

FIG. 12 is a diagram showing an overview of content playback controls inthe content playback system.

EMBODIMENT OF THE INVENTION

The following is a description of a preferred embodiment of the presentinvention with reference to the appended drawings. In the drawings,components denoted by the same reference numbers have the same orsimilar configurations. In the following description, the time for eachtiming is denoted using the hh:mm:ss format (where hh is the hour, mm isthe minute, and ss is the second). Note that the format used to expressthe timing is not limited to time information and may be expressed, forexample, as timer values incremented in a fixed cycle.

In the following explanation, the content playback system in theembodiment (referred to simply as the “content playback system” below)is used for content including a live performance on stage. However, theembodiment is not limited to this particular example.

<1. System Overview>

FIG. 1 is a diagram showing the overall configuration of the contentplayback system. As shown in FIG. 1, this content playback systemcomprises an operator terminal 100, user terminals 200 a, 200 b and 200c (content playback devices, referred to collectively as “the userterminals 200” when they do not have to be distinguished from eachother), and speakers 300 a, 300 b (referred to collectively as “thespeakers 300” when they do not have to be distinguished from eachother).

The speakers 300 are installed in the facility where the liveperformance is to be held, such as a theater or ballpark, and theoperator terminal 100 is operated by a person (operator) to control thecontent outputted from the speakers 300 such as background music (forexample, playing background music). The user terminals 200 areassociated with playback of this content to play additional content suchas subtitles or an audio guide. The performers performing live on thestage and the devices installed at the facility such as the operatorterminal 100 and the speakers 300 are referred to collectively as “stageside.”

In an example in which the content includes a live performance on astage, sub-content such as background music (second sub-content) isplayed back by the operator on the operator terminal 100 as the contentperformed on the stage (the main content) progresses. The user terminals200 automatically play additional sub-content such as subtitles (firstsub-content) using two tables for reflecting the deviation from thescheduled progress in the live performance due to fluctuations thereinwhile the background music is played back by the operator in accordancewith the live performance. An overview of the content playback system inthe present example will now be described with reference to (1) to (3)below. The content included in the content playback system, as mentionedabove, is divided broadly into main content, first sub-content, andsecond sub-content. Each type of content will be described in detailbelow.

(1) In the live performance using the content playback system, aplayback schedule is set before the performance for the background musicand subtitles based on scheduled progress in the live performance, whichis the main content, on the stage. Next, a synchronization point is setin a section of the performance during which the background music isplayed. More specifically, a synchronization point ID is embedded aswatermark data in the playback timing for the section during which thebackground music is played referencing the synchronization referencetiming such as the start time of the live performance. Setting theschedule and the synchronization point may entail registering settinginformation in the operator terminal 100 for the operator to edit whennecessary.

Here, a “synchronization point” is a point used to synchronize progressof sub-content with progress of the main content. A “synchronizationpoint ID” is identification information used to specify asynchronization point. The “synchronization reference timing” is thetiming such as the start time for the live performance or the start timefor a scene switch. In the following explanation, the synchronizationreference timing uses the start time “00:00:00” of the main content.

(2) The user terminals 200 used in the content playback system store (anaccessible) first table for associating and storing a synchronizationpoint ID with the scheduled timing for a synchronization pointreferencing the synchronization reference timing, and second table forstoring the schedule start timing for first sub-content such assubtitles to be played based on progress in the live performancereferencing the synchronization reference timing.

(3) When the live performance (main content) has started on the date ofthe live performance, the stage-side operator monitors progress of themain content. When a delay occurs, the playback timing for thebackground music is adjusted accordingly. As a result, the backgroundmusic is played on timing corresponding to actual progress in the liveperformance, and a synchronization point ID is outputted while thebackground music is being played. When the background music is receivedby the microphone in the user terminals 200, the synchronization pointID embedded in the background music is detected and the scheduled timingfor the synchronization point is obtained based on the detectedsynchronization point ID and the first table. In the content playbacksystem, the discrepancy between the scheduled timing for the acquiredsynchronization point and the detected timing of the synchronizationpoint ID (that is, the deviation from the schedule due, for example, toa delay) is obtained, and the timing for actually starting the subtitlesis determined based on the discrepancy and the second table to reflectthe deviation from the scheduled progress in the live performance. Inthe content playback system, the subtitles are then played on the userterminal 200 based on the determined start timing.

In this configuration, playback of first sub-content can be controlledbased on any timing not limited to the embedded timing of watermark datafor second sub-content such as background music when main content suchas a live performance experiences a fluctuation in the progress times.

In this configuration, playback of subtitles on user terminals 200 canbe synchronized with progress on stage with only small errors withoutthe operator having to perform any subtitle playback operation as thelive performance progresses.

<2. Hardware Configuration>

FIG. 2 is a diagram showing an example of the hardware configuration ofthe operator terminal 100 and the user terminals 200 (referred to belowsimply as the “user terminal 200”). The user terminal 200 can be anyterminal able to play back the first sub-content, such as a smartphone,tablet, notebook computer, desktop computer, or wearable terminal in theform of glasses or a wristband. As shown in FIG. 2, the user terminal200 has a processor 110, a storage device 115, a communication interface(I/F) 120, an audio input device 125, an audio output device 130, anoperation input device 135, and a display output device 140.

The processor 110 is a processing device for calculating, processing andtransferring data, executing programs, and controlling other devices.The processor 110 can realize these functions in the user terminal 200by executing a program stored in the storage device 115.

The storage device 115 stores programs and data and can be a primarystorage device (such as volatile memory or random access memory), anauxiliary storage device (such as nonvolatile memory), or an externalstorage device.

The communication interface 120 is a device used to exchange programsand data with external devices. The communication interface 120 can bean interface for a mobile phone communication network or a wirelesslocal area network (LAN). The communication interface 120 may also be awired interface.

The audio input device 125 detects ambient sound. The audio input device125 can be, for example, a microphone. The audio input device 125 candetect sound in the audible range or sound in the inaudible range. Theaudio input device 125 may also be external to the user terminal 200.

The audio output device 130 outputs audio. The audio output device 130can be, for example, a speaker. The audio output device 130 can alsooutput audio to an earphone. When the first sub-content includes audio(such as an audio guide or voice dubbing), the audio can be outputted tothe audio output device 130.

The operation input device 135 receives operation input from the user oroperator. The operation input device 135 can be a touch panel integratedinto the display output device 140. The operation input device 135 maybe external to the user terminal 200 such as a keyboard or mouse.

The display output device 140 displays video (including still images).The display output device 140 can be a liquid crystal display or organicelectroluminescence (EL) display. The display output device 140 may alsobe external to the user terminal 200. When the first sub-contentincludes video (such as subtitles), the video can be outputted to thedisplay output device 140 in the user terminal 200.

<3. Function Configuration> <3.1 Function Configuration of OperatorTerminal 100>

FIG. 3 is a diagram showing an example of the function configuration forthe operator terminal 100. The operator terminal 100 includes an inputunit 150, an output unit 155, a control unit 160, and a storage unit165. Each unit shown in FIG. 3 can use a storage area in the storagedevice 115, and be realized by having the processor 110 execute aprogram (content playback program) stored in the storage device 115.

The input unit 150 receives various types of information inputted to theoperator terminal 100. The input unit 150 can receive, for example,input related to the playback of second sub-content from the operator.The input unit 150 includes various types of input modes such asreceiving input from a keyboard connected to the operator terminal 100or audio inputted via a built-in microphone in the operator terminal100.

The output unit 155 outputs various types of information on the operatorterminal 100. The output unit 155 includes various types of output modessuch as displaying information on a screen in the operator terminal 100or outputting audio from a built-in speaker in the operator terminal100. The output unit 155 may also output the second sub-content.

The control unit 160 controls playback of the second sub-content basedon input received by the input unit 150.

The storage unit 165 may also store second sub-content. The storage unit165 may also store operation data indicating operations performed by theoperator.

<3.2 Function Configuration and Playback Control Mechanism of UserTerminal 200>

The playback control mechanism for the content playback system will beexplained first with reference to FIG. 5 and FIG. 6. In FIG. 5 and FIG.6, the main content is a live performance on the stage. The secondsub-content is BGM1 and BGM2 played during the live performance, and thefirst sub-content is subtitle 1 and subtitle 2 on the user terminal 200aligned with the live performance and the background music.

Here, the progress time for the main content fluctuates. The maincontent can be a live play or dance performed by people or a live showusing animals. The main content is referenced to control playback of thesub-content. The synchronization reference timing is set for the maincontent to serve as a reference for synchronizing playback of thesub-content.

The first sub-content is played back on a user terminal 200 based onprogress of the main content. Examples of this type of sub-contentinclude text data (such as subtitles or a guide), audio (such as musicor an audio guide), video (such as sign language images or explanatoryimages), effects involving light or vibrations (such as flashing lightson the terminal, vibration of the terminal, or penlights connected tothe terminal). When the main content is a live performance, the firstsub-content may be text such as subtitles whose play back is linked tothe live performance.

The second sub-content is content played back based on the progress ofthe main content with the first sub-content. The second sub-content canbe played back on a device such as speakers 300 installed in a facilitysuch as a theater based on an operation performed by the operator on theoperator terminal 100. This sub-content can be audio (background musicor sound effects), video (live video or background video), or a lightshow (spotlights and lasers). Watermark data for controlling playback ofthe first sub-content is embedded in the second sub-content so thatplayback of the first sub-content can be controlled based on playback ofthe second sub-content. The “watermark data” can be specific information(a “synchronization point ID” in the present example) embedded in videoor music content using any electronic watermarking technology.

FIG. 5 shows the preset content playback schedule. In the example shownin FIG. 5, the live performance start time on the stage used as thesynchronization reference timing is 00:00:00. BGM1 is scheduled to startplaying at 00:05:00 and BGM2 is scheduled to start playing at 00:30:00.

In the user terminal 200, Subtitle 1 is scheduled to start playing at00:12:00 and Subtitle 2 is scheduled to start playing at 00:43:00. InFIG. 5, the P in a circle denotes the point at which Subtitle 2 is to bestarted during the live performance (“point P” below). In the schedule,the timing for point P is scheduled to coincide with the scheduled starttiming for Subtitle 2.

In FIG. 6, on the date of the live performance, the live performance isbehind schedule on the stage because of a longer than anticipatedperformance by the performer (resulting in a one second delay in thepresent example). The schedule playback timing for the background musicis corrected by the operator after the delay to be played five minuteslater than originally scheduled. In FIG. 6, the playback timing for thebackground music after the delay is 00:35:00, which is five minuteslater than the originally scheduled 00:30:00.

In FIG. 6, the content playback system in the user terminal 200 absorbsthe delay in the performance and synchronizes Subtitle 2 with progressin the performance. More specifically, when the synchronization point IDfor the watermark data embedded in BGM2 is ID:002 and is outputted alongwith BGM2, the user terminal 200: (1) detects the synchronization pointID; and (2) acquires the scheduled timing (00:30:00) for thesynchronization point ID (ID:002) based on the detected synchronizationpoint ID and on the first table in which the synchronization point IDhas been associated with the scheduled timing for the synchronizationpoint, and acquires the difference between the acquired scheduled timingand the timing (00:35:00) at which the synchronization point ID wasdetected. The user terminal 200 then (3) determines the start timing forSubtitle 2 (00:48:00), which reflects the difference relative to thepreset scheduled start timing (00:43:00), and starts playback ofSubtitle 2 at the new start timing.

In this configuration, playback of first sub-content such as subtitlescan be started at the appropriate time aligned with the delayed progressin the main content such as a live performance when a delay occurs inthe main content or live performance on stage and progress fluctuatesfrom the schedule.

FIG. 4 is a diagram showing an example of the function configuration forthe user terminal 200. The user terminal 200 includes a detecting unit210, an acquiring unit 215, a determining unit 220, a control unit 225,and a storage unit 230. Each unit in FIG. 4 uses a storage area in thestorage device 115, and the processor 110 can realize these units in theuser terminal by executing a program (content playback program) storedin the storage device 115.

The detecting unit 210 detects a synchronization point ID embedded aswatermark data from second sub-content played back based on progress inthe main content.

The acquiring unit 215 acquires the timing for the synchronization pointbased on the synchronization point ID detected by the detecting unit 210and the first table. The acquiring unit 215 acquires the differencebetween the timing for the acquired synchronization point and the timingat which the synchronization point ID was detected in reference to thesynchronization reference timing.

The determining unit 220 determines the start timing for the firstsub-content based on the difference acquired by the acquiring unit 215and the second table.

The control unit 225 controls playback of the first sub-content based onthe start timing for the first sub-content determined by the determiningunit 220.

The storage unit 230 stores the first table and the second table. Thestorage unit 230 may also store the third table described later. Notethat the storage unit 230 may use a file system or a database systemsuch as RDB or NoSQL to store the tables. The storage unit 230 may alsostore the content playback program.

<Table Configuration>

The first table 410 and the second table 420 will now be described withreference to FIG. 7. In order to make the tables easier to understand,the information is associated directly and stored in a single table.However, the present invention is not limited to this table format. Forexample, information can be associated and stored indirectly acrossmultiple tables.

As shown in FIG. 7, the first table 410 associates and storessynchronization point IDs 412 with scheduled synchronization timings414. The first table 410, for example, associates and storessynchronization point ID 412 “001” with scheduled synchronization timing414 “00:05:00” specified by the synchronization point ID. Note that thescheduled synchronization timing 414 may be set to any timingreferencing the synchronization reference timing based on, for example,progress in the live performance or editing of the first sub-content forthe main content. More specifically, the scheduled synchronizationtiming 414 may be set at intervals of five seconds, ten seconds, oneminute etc. from the synchronization reference timing, and each BGM maybe set to the timing at which playback starts.

The second table 420 stores the scheduled start timings 422 for thefirst sub-content with reference to the synchronization referencetiming. The second table 420 may associate and store schedule starttimings 422 with information indicating the first sub-content (“firstsub-content information” below). First sub-content information can be,for example, identification information for specifying firstsub-content. First sub-content information may include, for example, afirst sub-content ID, the title of the first sub-content, the file namecontaining the first sub-content, and the file path. The second table420 may associate and store, for example, the schedule start timing 422for first sub-content (00:45:00) with the first sub-content informationscheduled to start (video 1).

In addition to the units described above, the user terminal 200 may alsoinclude a content acquiring unit (not shown). The content acquiring unitmay, for example, acquire the first sub-content to be controlled andplayed back by the user terminal 200 and the content playback program tobe executed by the user terminal 200 via the internet or an externalmedium, and store the sub-content and the program in the storage unit230. In the user terminal 200, the first sub-content does not have to beacquired by the content acquiring unit and stored in the storage unit230. For example, the user terminal 200 may playback first sub-contentstored in another terminal via a playback control message sent from theuser terminal 200.

<4. Processing Flow>

FIG. 8 is a flowchart showing an example of the content playbackprocessing in the user terminal 200. The processing shown in FIG. 8 canbe triggered, for example, by an install request from the user for anapplication including the content playback program or the user launchingsuch an application. The order of the processing below is just that ofan example and may be changed when necessary.

As shown in FIG. 8, the user terminal 200 detects a synchronizationpoint ID embedded as a watermark in second sub-content to be played backbased on progress of the main content (S701).

The user terminal 200 then acquires the timing for the synchronizationpoint based on the detected synchronization point ID and the first table(S702). Next, the user terminal 200 acquires the difference between theacquired scheduled timing at the synchronization point and the timing atwhich the synchronization point ID was detected with reference to thesynchronization reference timing (S703). The user terminal 200 thendetermines the start timing for the first sub-content based on theacquired difference and the second table (S704).

Next, the user terminal 200 controls playback of the first sub-contentbased on the determined start timing for the first sub-content (S705).

The embodiment described above was provided so that the presentinvention could be easily understood, and should not be interpreted aslimiting the present invention in any way. The arrangement, materials,conditions, shapes and sizes of the various component in the embodimentare for illustrative purposes only and can be changed when necessary.These can also be partially replaced or combined with componentsdescribed in other embodiments.

(Modifications)

The present invention was described with reference to the embodimentprovided above. However, the present invention is not limited to thisembodiment. The present invention, for example, encompasses thefollowing modifications as well.

(1) In the embodiment described above, the main content was a liveperformance whose progress time fluctuates. However, the presentinvention can also be applied to content such as movies and live videoin which the progress time does not change substantially. For example,when the main content is a movie, the first sub-content may be subtitlesfor the movie. Even when the progress time of the main content does notchange at all, there may be system delays between the device playing themain content, the operator terminal 100 and the user terminals 200. Inthis case, the delays between content can be substantially eliminatedusing the present invention. When the present invention is used in thisway, playback control of the first sub-content is controlled with thedifference between the detection timing at which a synchronization pointID was acquired according to the system time and the scheduled timingfor the synchronization point associated with the synchronization pointID in the first table 410.

(2) In the embodiment described above, the control unit 225 controlledplayback of the first sub-content based on the start timing determinedby the determining unit 220. However, when at least one secondsub-content is set as a prerequisite for the playback of the firstsub-content, the first sub-content may be played back only on conditionthat the synchronization point ID embedded in the second sub-content hasbeen detected.

The configuration of the control unit 225 in this modification will beexplained with reference to FIG. 9 and FIG. 10. FIG. 9 is a diagramshowing an overview of an example of a content playback event. FIG. 10is a diagram showing an overview of the content playback controls in thecontent playback system for the event in FIG. 9.

As shown in FIG. 9, playback of first sub-content Subtitle 1 andSubtitle 2 is set so that playback of Subtitle 2 occurs automaticallyafter Subtitle 1 in alignment with the timing of point P in a liveperformance and second sub-content BGM2. When a delay occurred in thelive performance that is the main content (a three-minute delay in thisexample), Subtitle 2 is outputted to user terminal 200 at 00:20:00before the synchronization point ID for second sub-content BGM2. WhenBGM2 is detected, the difference in the detection timing due to thedelay is acquired and the start timing determined. As a result, Subtitle2 is outputted again at 00:23:00. Here, “occurs automatically” meanseach process is started and executed in a user terminal 200 without atrigger such as a send message from the outside. For example, theplayback time for each first sub-content is scheduled beforehand in aschedule and each first sub-content is played back in successive orderbased on the registered playback schedule.

For this event, as shown in FIG. 10, the control unit 225 presets BGM2as second sub-content, which is a prerequisite for the playback of firstsub-content Subtitle 2, so that Subtitle 2 is played back on conditionthat synchronization point ID:001 for BGM2 is detected by the detectingunit 210. As a result of this control process, playback of Subtitle 2goes into standby when there is a delay in the progress of the liveperformance and Subtitle 2 is played back once the synchronization pointID for BGM2 has been detected. In this example, playback of the firstsub-content occurs automatically but the first sub-content can be playedback in alignment with second sub-content in response to progress of themain content even when playback of the main content is delayed. As aresult, a content playback system can be provided that is easy for usersto use.

FIG. 11 is a flowchart showing an example of content playback controlprocessing performed by a control unit 225 with the configurationdescribed above. As shown in FIG. 11, the user terminal 200 acquires thecurrent time (for example, the system time in the user terminal 200) anddetermines whether there is first sub-content whose start timing is atthe acquired current time (S711). This process is either event-driven oron a fixed cycle. When there is no first sub-content with this starttiming (NO in S711), the process ends.

When there is first sub-content with this start timing (YES in S711),the user terminal 200 determines whether there is second sub-content,which is a prerequisite for the playback of the first sub-content(S712). When there is such second sub-content (YES in S712), it isdetermined whether the synchronization point ID embedded in the secondsub-content has been detected (S713). When it has been determined thatthe synchronization point ID has been detected (YES in S713), the userterminal 200 plays the first sub-content based on the start timing forthe first sub-content (S714). When it has been determined that thesynchronization point ID has not been detected (NO in S713), the processends.

When there is no second sub-content which is a prerequisite for theplayback of the first sub-content (NO in S712), the user terminal 200plays the first sub-content based on the start timing for the firstsub-content (S714).

(3) In the embodiment described above, the watermark data detected bythe detecting unit 210 may be data embedded in sound in the inaudiblerange. In this example, watermark data for a synchronization point IDembedded in sound can be outputted in a section in which secondsub-content such as background music is not arranged so that the userremains unaware of the sound in the inaudible range.

(4) In the embodiment described above, content playback control wasperformed by the control unit 225 using a first table and a secondtable. However, the present invention may also include a third table forassociating and storing synchronization point IDs with first sub-contentinformation, and a second control unit 2 for controlling playback offirst sub-content indicated by the first sub-content informationassociated with a synchronization point ID based on the detectedsynchronization point ID and the third table. For example, when thedetected synchronization point ID is not stored in the second table butthe detected synchronization point ID is stored in the third table, thesecond control unit controls playback of the first sub-contentassociated with a synchronization point ID based on the detectedsynchronization point ID and the third table.

In this configuration, (1) the first table 410 and the second table 420are used in sections in which the first sub-content runs automaticallyas in the prior art, and (2) the first table 410 and the third table areused in sections in which the first sub-content is to be started inalignment with the playback timing of the second sub-content (the timingembedded in watermark data etc.). In this way, playback control can berealized for two different types of first sub-content. In thisconfiguration, many different variations can be created for contentplayback control without the user having to input operations.

(5) In Modification (4), the third table is separate from the firsttable 410. However, it may also be merged with the first table 410 tocreate a single table. More specifically, the third table may beintegrated with the first table 410 by providing three columns, one eachfor the first synchronization point ID serving as the main key, thescheduled synchronization timing, and the first sub-content information,or may be integrated by combining the column for the scheduledsynchronization timing and the first sub-content information. In thisconfiguration, the number of tables can be reduced and a more efficientcontent playback system can be realized.

(6) In the embodiment described above, the first sub-content (subtitles)were played back in series. However, as shown in FIG. 12, the firstsub-content can be divided into first sub-content 1 and firstsub-content 2 so that a user terminal 200 can simultaneously playbackmore than one first sub-content in parallel. In another example, oneuser terminal 200 a can play back first sub-content 1 and another userterminal 200 b can play back first sub-content 2 when more than one userterminal 200 is being used. Also, as shown in FIG. 12, synchronizationpoint IDs “ID:001” and “ID:002” are set for BGM1 and synchronizationpoint ID “ID:003” is set for BGM2. Here, there is no 1:1 correspondencebetween second sub-content units and the number of synchronizationpoints set. This allows one-to-many, many-to-one and many-to-manycorrespondences to be used.

In this configuration, first sub-content can be flexibly played backseveral times by a user terminal 200 using watermark data once, and ahighly scalable content playback system can be provided.

(7) While not depicted in the embodiment described above, a userterminal 200 may also use a light-emitting device such as a warninglight or an LED light on a smartphone. When first sub-content includes alight show, some of the light in the performance can be emitted by thelight-emitting device. In this configuration, a content playback systemcan be provided that can utilize user terminals 200 to realize varioustypes of effects in a venue in alignment with progress in the maincontent, and that users may find interesting.

(8) In the embodiment described above, electronic watermarks are used todetect synchronization point IDs. However, audio fingerprintingtechnology may also be used. Audio fingerprinting technologies aredigital audio signal processing technologies that electronically extractaudio waveform features from original digital sound sources and to useextracted features smaller than the original sound source as(fingerprint) data. In the content playback system, audio waveformfeatures from sound received by the audio input terminal 125 areextracted and checked against audio waveform learning data stored in thestorage device 115 to detect a synchronization point ID.

In this configuration, a distinctive feature obtained from the originalsecond sub-content can be used to detect a synchronization point withouthaving to embed watermark data in the second sub-content. In this way, ageneral-purpose content playback system can be provided.

Key to the Drawings

100: Operator terminal

110: Processor

115: Storage device

120: Communication interface

125: Audio input device

130: Audio output device

135: Operation input device

140: Display output device

150: Input unit

155: Output unit

160: Control unit

165: Storage unit

200, 200 a, 200 b, 200 c: User terminals

210: Detecting unit

215: Acquiring unit

220: Determining unit

225: Control unit

230: Storage unit

300, 300 a, 300 b: Speakers

410: First table

420: Second table

1. A content playback program stored on a computer readable medium of acomputer, wherein the execution of the content playback program causesthe computer to perform a method comprising: utilizing a first table forassociating and storing a synchronization point ID embedded as watermarkdata with a scheduled timing for the synchronization point based on asynchronization reference timing for the main content; utilizing asecond table for storing a scheduled start timing for first sub-contentbased on the synchronization reference timing; detecting thesynchronization point ID embedded as watermark data from secondsub-content played back based on the progress of the main content;acquiring the scheduled timing for the synchronization point based onthe detected synchronization point ID and the first table, and acquiringthe difference between the scheduled timing of the acquiredsynchronization point and the detection timing for the synchronizationpoint ID based on the synchronization reference timing; determining astart timing for the first sub-content based on the acquired differenceand the second table; and controlling playback of the first sub-contentbased on the determined start timing for the first sub-content.
 2. Thecontent playback program according to claim 1, wherein controllingplayback of the first sub-content is based on condition that thesynchronization point ID embedded in the premised second sub-content isdetected when at least one second sub-content has been set as aprerequisite for the playback of the first sub-content.
 3. The contentplayback program according to claim 1, wherein the watermark dataincludes data embedded in sounds in the non-audible area.
 4. The contentplayback program according to claim 1, wherein the main content includesa live performance, the first sub-content is text data to be played backbased on the progress of the main content along with the secondsub-content, and the second sub-content is music to be played back basedon the progress of the main content.
 5. The content playback programaccording to claim 3, wherein the execution of the content playbackprogram causes the computer to perform a method comprising: utilizing athird table for associating and storing the synchronization point IDwith information indicating the first sub-content; and controllingplayback of the first sub-content indicated in the informationassociated with the synchronization point ID based on the detectedsynchronization point ID and the third table when the synchronizationpoint ID has been detected by the detection function.
 6. A contentplayback method comprising: associating and storing a synchronizationpoint ID embedded as watermark data with a scheduled timing for thesynchronization point based on a synchronization reference timing forthe main content in a first table; storing a scheduled start timing forfirst sub-content based on the synchronization reference timing in asecond table; detecting the synchronization point ID embedded aswatermark data from second sub-content played back based on the progressof the main content; acquiring the scheduled timing for thesynchronization point based on the detected synchronization point ID andthe first table, and acquiring the difference between the scheduledtiming of the acquired synchronization point and the detection timingfor the synchronization point ID based on the synchronization referencetiming; determining a start timing for the first sub-content based onthe acquired difference and the second table; and controlling playbackof the first sub-content based on the determined start timing for thefirst sub-content.
 7. A content playback system comprising a userterminal and an operator terminal, wherein the user terminal comprises:a first table for associating and storing a synchronization point IDembedded as watermark data with a scheduled timing for thesynchronization point based on a synchronization reference timing forthe main content, a second table for storing a scheduled start timingfor first sub-content based on the synchronization reference timing, adetecting unit for detecting the synchronization point ID embedded aswatermark data from second sub-content played back based on the progressof the main content, an acquiring unit for acquiring the scheduledtiming for the synchronization point based on the detectedsynchronization point ID and the first table, and acquiring thedifference between the scheduled timing of the acquired synchronizationpoint and the detection timing for the synchronization point ID based onthe synchronization reference timing, and a determination unit fordetermining a start timing for the first sub-content based on theacquired difference and the second table, and a control unit forcontrolling playback of the first sub-content based on the determinedstart timing for the first sub-content; and the operator terminalcomprises: an input unit for receiving input related to the playback ofthe second sub-content from an operator, and a control unit forcontrolling playback of the second sub-content based on the content ofthe received input.
 8. The content playback program according to claim2, wherein the watermark data includes data embedded in sounds in thenon-audible area.
 9. The content playback program according to claim 2,wherein the main content includes a live performance, the firstsub-content is text data to be played back based on the progress of themain content along with the second sub-content, and the secondsub-content is music to be played back based on the progress of the maincontent.
 10. The content playback program according to claim 3, whereinthe main content includes a live performance, the first sub-content istext data to be played back based on the progress of the main contentalong with the second sub-content, and the second sub-content is musicto be played back based on the progress of the main content.